Description of problem:
NPE on package delete

Version-Release number of selected component (if applicable):
5.5.0 final

How reproducible:

Use java project with drools builder
Or Create drools project


Steps to Reproduce:
1. Create source package
2. Create number of classes in package
3. Delete package

Actual results:


Expected results:


Additional info:

java.lang.NullPointerException
	at org.drools.eclipse.builder.DroolsBuilder.exists(DroolsBuilder.java:495)
	at org.drools.eclipse.builder.DroolsBuilder.parseResource(DroolsBuilder.java:567)
	at org.drools.eclipse.builder.DroolsBuilder$DroolsBuildDeltaVisitor.visit(DroolsBuilder.java:478)
	at org.eclipse.core.internal.events.ResourceDelta.accept(ResourceDelta.java:69)
	at org.eclipse.core.internal.events.ResourceDelta.accept(ResourceDelta.java:80)
	at org.eclipse.core.internal.events.ResourceDelta.accept(ResourceDelta.java:80)
	at org.eclipse.core.internal.events.ResourceDelta.accept(ResourceDelta.java:49)
	at org.drools.eclipse.builder.DroolsBuilder.incrementalBuild(DroolsBuilder.java:425)
	at org.drools.eclipse.builder.DroolsBuilder.build(DroolsBuilder.java:353)
	at org.eclipse.core.internal.events.BuildManager$2.run(BuildManager.java:728)
	at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42)
	at org.eclipse.core.internal.events.BuildManager.basicBuild(BuildManager.java:199)
	at org.eclipse.core.internal.events.BuildManager.basicBuild(BuildManager.java:239)
	at org.eclipse.core.internal.events.BuildManager$1.run(BuildManager.java:292)
	at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42)
	at org.eclipse.core.internal.events.BuildManager.basicBuild(BuildManager.java:295)
	at org.eclipse.core.internal.events.BuildManager.basicBuildLoop(BuildManager.java:351)
	at org.eclipse.core.internal.events.BuildManager.build(BuildManager.java:374)
	at org.eclipse.core.internal.events.AutoBuildJob.doBuild(AutoBuildJob.java:143)
	at org.eclipse.core.internal.events.AutoBuildJob.run(AutoBuildJob.java:241)